This invention relates to an improved electric starter for an internal combustion engine.
In the past there have been numerous methods devised involving mechanisms to smoothly engage and reliably maintain engagement during the cranking cycle and, then, to smoothly disengage the starter from the engine once the engine has started. These methods have all either fallen short of one or more of the objectives or have resulted in bulky, heavy, and costly mechanisms making them impractical for many applications. For example, these earlier approaches include the use of a solenoid, the purpose of which is to move the drive axially on the starter shaft for engagement with the member on the engine to be rotated and to hold the drive in contact with the member during cranking.
Another approach, usually used on small engines and correspondingly smaller starters, is the use of drives that depend entirely on the acceleration of the armature shaft and the inertia of drive to provide axial movement of the drive along threaded areas between the drive and rotating shaft and, thereby, provide initial engagement of the drive with the engine member. This type drive has an undesirable characteristic, however, in that it is susceptible to premature disengagement from the engine rotating member resulting in false starts and, therefore, requiring repetitive attempts to start the engine. To overcome this problem, numerous approaches have been taken to lock this type drive into engagement with the engine. All of these approaches have been less than satisfactory, at least in part, because the various locking in mechanisms would stick and, thereby, not allow disengagement between the rotating engine member and the drive after cranking.